[WFCORE-186] Bring default schema versions in use up to 3.0
Upgrade MSC to 1.2.4.Final
Merge pull request #267 from dmlloyd/msc-1.2.4

Upgrade MSC to 1.2.4.Final
Merge pull request #253 from darranl/WFCORE-186

[WFCORE-186] Bring default schema versions in use up to 3.0
[WFCORE-196] Don't call ManagedServerProxy.disconnected with the ManagedServer lock held; register ManagementChannelHandler as a channel CloseHandler